Pistols love heavier than 0.25g, I've gotten kills out to 140ft using my G19 and 0.36g BBs. Sure you have to aim a foot above the head in order to hit the chest, but holy crap do they hit hard and make the guys not want to trade fire with you. Lol
I use minimum 0.28g in my pistols, and try to keep my MK23 rounds as 0.30g when I can, largely when I use it in slient mode.
An example of heavier rounds for accuracy, at 30ft in my basement, I've gotten 1.5" groups using my MK23 GBB in silent mode, double action (slide doesn't cycle making for more accurate shots) firing. And with 0.28g in my G19, good groups end up being around 2-3". This coming from a barrel about as long as your index finger.